The present invention relates generally to hydraulic elevators and, in particular, to a self-balancing synchronization assembly for a jack in a hydraulic elevator.
Hydraulic elevator systems are well known. Such systems include an elevator car movable along guide rails within a hoistway, and a jack with at least one telescoping piston slidably received in a corresponding cylinder supporting and moving the elevator car. A pressurized working fluid, such as oil, is introduced into or removed from the volume between the telescoping piston and the interior of the cylinder in order to reciprocate the piston and move the elevator car vertically within the hoistway.
If the hydraulic elevator utilizes two or more telescoping pistons, a synchronizing device must be provided to coordinate movement of the pistons. The Swiss patent publication 463 745 shows an elevator with a hydraulic or pneumatic telescopic ram having two or three pistons. A mechanical connecting means engages between the telescopic parts and in each stroke ensures uniformly distributed part strokes between the successive telescopic parts. Chains or cables deflected over rollers are, in particular, used as the mechanical connecting means.
The U.S. Pat. No. 6,098,759 shows another hydraulic elevator construction having a pair of ropes connected at one end to a crossbeam mounted on the guide rails at the top end of the hoistway. The elevator car is supported by a jack of the two-stage type with an intermediate piston and a lower piston telescopically extending from an upper cylinder. The other end of each rope is attached to a sleeve on the cylinder. An intermediate portion of each rope extend below the ends and passes over an associated sheave rotatably mounted on an intermediate piston of the jack thereby changing direction by 180 degrees.
The known synchronizing devices have problems such as requiring room at the top of the hoistway for mounting and typically being custom designed to fit the particular hoistway configuration. The multiple synchronization cables require individual adjustment for retensioning either at the hoistway mounting point or at the attachment point on the jack flange.
The present invention concerns a self-balancing synchronization assembly for a hydraulic elevator system. The synchronization assembly includes a support beam which mounts via a pivoting pin to an elevator car guide rail, rather than the piston flange as in the prior art. The support beam has first and second ends that extend on either side of the guide rail. On the first end, the beam supports the downward load of at least one pair of synchronization cables. On the second end, a support cable extends downwardly to the elevator pit and attaches to the pit floor via a turnbuckle or similar tensioning device. The corresponding synchronization cables for each piston flange and the support cable mount to a synchronization bracket and support bracket, respectively, each of which is attached to the support beam by a pivoting pin connection. The pivoting connection allows the matching two synchronization cables for each piston flange to equalize loads. The synchronization cables create a resultant downward load on the first end of the pivoting support beam. A load, therefore, is required on the second end of the support beam to balance the synchronization load, which is accomplished by the support cable mounted to the support bracket on the second end of the support beam. The support cable extends to the elevator pit or hoistway floor, which advantageously allows cable tensioning from a single point at the elevator pit floor.
The synchronization assembly according to the present invention also eliminates all hoistway wall or overhead attachment interfaces, which permits tensioning of the cables in the hoistway pit, which is easier to access and has more structural strength than connections at the hoistway walls or the piston flanges.
In addition, the present invention allows the installation of the same equipment regardless of the building type because the present invention uses a single beam design for all variations of hoistway width and construction type.
Furthermore, the present invention can be used to synchronize two-stage and three-stage hydraulic elevators because each pair of synchronization cables is attach to a separate synchronization bracket.